UMT MOOC: Ornamental Fish Culture - Topic 7: Seed Production - Factors to be Considered for Feeding - Species & Water Medium

Continue from previous post.

Besides the consideration of tank or pool size when rearing larvae, fry, or hatchling, the next item we should look into is feeding in the grow-up tank or pool. We will go through all these factors that will influence the feeding as listed below:

(1) Species
Before a fish egg becomes a fry, it have to go through different development stages of the body parts which consists of: (1) incubation period, (2) eye pigment, (3) mouth formation, (4) fins development, (5) digestion system. Different species have different body and egg sizes. Hence, feeding volume should take this into the consideration. For example, feeding an Arowana fry is totally different from Betta sp. fry as both species have different rate of growth development. An Arowana fry have bigger yolk-sac volume than a Betta sp. fry. Furthermore, ornamental fish values is based on its colours and patterns. Hence, diet that promotes good pigmentation in term of certain colours and patterns should be factored in as well.

(2) Water medium
This is something that we never thought off. Using "Green water" when feeding the fry after the yolk-sac have been used up. Basically "Green water" is just plain fresh with Chlorella sp. (micro-algae which have green pigment due to Chlorophyll) which can serve as initial and additional live food for fry and juvenile fish. This means Chlorella sp. cannot be used as the only feed and must combined with other live food sources like Rotifier sp., Artemia (Miona nauplii) for optimal growth (one of the research paper I've reviewed indicates this as well).  For normal rate of larval rearing, the density level should be 10×3-5 cells with water changes every 7 till 10 days (it was in the slides, not sure why so).

There are two ways to produce Chlorella sp., either naturally or in the lab. For the former method, just take and a bucket of water and put it under the natural sunlight or artificial fluorescent light (similar to green algae found in your aquarium tank). The aged water will slowly turn greenish and you will have your Chlorella sp. If you need pure Chlorella sp. without any contamination, you can culture it within a lab or facility as shown in the video below.




No comments:

Post a Comment